The present invention relates to absorbent articles such as sanitary napkins, panty liners, adult incontinence devices, and the like. Still more particularly, the present invention concerns absorbent articles such as sanitary napkins, and the like having flaps with a deformed hinge and zones of extensibility for relieving the stresses that develop in the flaps when the flaps are folded down and under a wearer""s undergarment.
Absorbent articles, particularly sanitary napkins, having wings or flaps are disclosed in the patent literature and are available in the marketplace. Sanitary napkins having flaps of the various types are disclosed in U.S. Pat. No. 4,687,478, entitled xe2x80x9cShaped Sanitary Napkin With Flapsxe2x80x9d, which issued to Van Tilburg on Aug. 18, 1987, U.S. Pat. No. 4,608,047, entitled xe2x80x9cSanitary Napkin Attachment Meansxe2x80x9d, which issued to Mattingly on Aug. 26, 1986, U.S. Pat. No. B1 4,589,876, entitled xe2x80x9cSanitary Napkinxe2x80x9d, which issued to Van Tilburg on May 20, 1986, U.S. Pat. No. 4,285,343, entitled xe2x80x9cSanitary Napkinxe2x80x9d, which issued to McNair on Aug. 25, 1981, U.S. Pat. No. 3,397,697, entitled xe2x80x9cDisposable Sanitary Shield For Undergarmentsxe2x80x9d, which issued to Rickard on Aug. 20, 1968, and U.S. Pat. No. 2,787,271, entitled xe2x80x9cSanitary Napkinxe2x80x9d, which issued to Clark on Apr. 2, 1957.
A number of variations on the types of flaps described above have been presented in an attempt to solve various problems. U.S. Pat. No. 4,900,320 issued to McCoy on Feb. 13, 1990, discloses a sanitary napkin having flaps affixed at points inward from the longitudinal edge of the napkin. U.S. Pat. No. 4,911,701 issued to Mavinkurve on Mar. 27, 1990, discloses a sanitary napkin having elastic means for providing greater convex shape to the body-facing portion of the central absorbent and for enabling adhesive-free placement of the flaps of the napkin. U.S. Pat. No. 4,940,462 issued to Salerno on Jul. 10, 1990, discloses a sanitary napkin with longitudinally expandable flaps. A sanitary napkin having flaps with stress relief means in the form of a notch or a slit is described in U.S. Pat. No. 4,917,697 which issued to Osborn, III, et al. on Apr. 17, 1990. U.S. Pat. No. 5,389,094 issued to Lavash et al. on Feb. 14, 1995, discloses sanitary napkins (and other types of absorbent articles) having flaps and zones of differential extensibility. Although these latter sanitary napkins work quite well, the search for sanitary napkins that are more cost effective, as well as those which have improved flaps has continued.
In accordance with the present invention, an absorbent article, such as a sanitary napkin, is provided. The sanitary napkin has flaps with a deformed hinge and zones of extensibility for relieving the stresses that develop in the flaps when the flaps are folded around and under the edges of the crotch of the wearer""s panties.
The sanitary napkin has a principal longitudinal centerline and a principal transverse centerline. The sanitary napkin comprises a main body portion and a pair of flaps joined to the main body portion. The main body portion of the sanitary napkin comprises a liquid pervious topsheet, a liquid impervious backsheet joined to the topsheet, an absorbent core positioned between the topsheet and the backsheet. The main body portion has two spaced apart longitudinal edges and two spaced apart transverse end edges.
The flaps are each joined to the main body portion at a juncture. The flaps extend laterally outward from at least a central region of the main body portion beyond the longitudinal side edges of the main body portion. In one preferred embodiment, the flaps are integral extensions of the topsheet and backsheet. The flaps are divided into a front half and a back half by a flap transverse centerline. The flaps each have two corner regions which are located adjacent the area of the ends of the junctures of the flaps with the main body portion. One corner region is located adjacent the area of the juncture in each direction remote from the principal transverse centerline. The sanitary napkin comprises a deformed hinge (or bending zone) located in a region that includes the juncture of the flaps with the main body portion and zones of differential extensibility in the corner regions of the flaps. The deformed hinge provides at least one axis about which the flaps may fold relative to the main body portion. The zones of differential extensibility allow the corner regions to extend outward (preferably in a generally transverse direction) to provide a means for the relief of stresses that develop in the flaps of the sanitary napkin when the sanitary napkin are folded down and under a wearer""s undergarments.
In an alternative embodiment, at least a portion of the deformed hinge comprises a portion of the sanitary napkin which has a strainable network formed therein. The strainable network comprises at least two visually distinct regions. The network is configured so that at least one of the regions, the second regions, have a surface-pathlength (dimension measured along the surface) which is greater than that of the other regions, the first regions. The second regions exhibiting the longer surface-pathlength preferably comprise one or more rib-like elements. The first regions with the shorter surface-pathlength are preferably substantially planar. In this embodiment, the portion of the deformed hinge comprising this type of strainable network is preferably located at least in the region of the flap transverse centerline.